ZURICH, Nov 30 (Reuters) - Russian sprinter Yulia Gushchina, part of the silver medal winning 4x400 metres relay team at the 2012 London Games, failed an anti-doping test, the International Olympic Committee said on Thursday.

Re-analysis of Gushchina's samples from London resulted in a positive test for banned substances dehydrochlormethyltestosterone and stanozolol, the IOC said in a statement, the latest sanction as it re-tests samples from Russian athletes.

It said it also disqualified Russian long jumper Anna Nazarova for doping.